Experts have criticised the government's decision to use foot troops and motorised sprays, saying these are not effective in combating the locusts, which can fly as high as 200 metres above the ground.

Dr Perpetra Akite, an entomologist at Makerere University College of Natural Sciences, said foot troops and vehicles cannot manage locusts. “These locusts are always on the move and they fly as high as 200 metres. So government needs aircrafts to spray them,” Dr Akite said.

She also faulted the government for procuring the wrong type of chemical to spray the locusts.

“These chemicals are not appropriate for aerial spray and they accumulate in environment amidst their bad effects on non-target living things,” Dr Akite said.

Dr Ekwaro Obuku, the former president of Uganda Medical Association, told Daily Monitor that the procured chemicals government have terrible effects on human health. He said government should have done sufficient consultations before procuring them.

“The ministry should first do environment impact assessment before embarking on the use of such dangerous chemicals. Some of these chemicals have been known to cause cancer in people,” Dr Obuku said.

More swarms arrive

The situation in Karamoja has become tense with more locust swarms crossing from Kenya.

Mr Martin Owor, the commissioner for disaster preparedness in Office of the Prime Minister, said the locusts had moved 50km inside Moroto District at Nakapat in Rupa Sub-county.

“The other swarms, which left Amudat District yesterday after landing there for about one hour in a place called Kosike and later flying to Nabilatuk/Nakapiripirit areas, about 100km inland, have today [yesterday] afternoon set-off flying backwards from Nabilatuk towards Amudat,” Mr Owor said.

He added that a much bigger swarm from deep inside Kenya yesterday landed at Kiwawa, three kilometres inside Kenya near the Uganda border and they appeared poised to enter Amudat or Moroto districts anytime. Mr Owor said the surveillance team was assessing the damage and loss.

“The ground surveillance teams of the districts of Amudat, Moroto, Napak, Nabilatuk and other areas of Karamoja Subregion are closely monitoring movement of the swarms. Spraying begins today,” he said.

“The swarm of locusts was reportedly seen at Alerek Hill in Labwor County, Abim District… Spray aircraft will arrive in Karamoja tomorrow [today]…Two international experts will join Ugandan experts in Karamoja,” Mr Owor added.

Mr Benius Tukahirwa, the senior inspector in the Crop Protection department at the Ministry of Agriculture, said the locusts are fast-moving insects and they expect them to spread to other districts in the next three weeks. He said they move in swarms, land on ground and lay eggs, eat all the green pasture and move to another area.

“We are not scared of the ones that have arrived in the country. The ones we are scared about are the next generation of swarms of locusts,” he added.

About locusts

A desert locust usually likes to live a shy, solitary life. It develops from an egg into a young locust - known as a hopper - and then into a flying adult. It’s a simple, if unremarkable, existence.

Such swarms of locusts can be huge. They can contain up to 10 billion individuals and stretch over hundreds of kilometres. They can cover up to 200km in a day, devastating rural livelihoods in their relentless drive to eat and reproduce.

Even an average swarm can destroy crops sufficient to feed 2,500 people for a year, according to the UN’s Food and Agriculture Organisation (FAO). The last major upsurge - a sharp rise in the number of swarms - in West Africa in 2003-05 cost $2.5bn in harvest losses, according to the UN.

But there were also large and damaging upsurges in the 1930s, 40s and 50s. Some of them spanned multiple regions, reaching the numbers required to be declared a “plague”.

Overall, the FAO estimates the desert locust affects the livelihood of one in 10 people on the planet - making it the world’s most dangerous migratory pest. The pests had already destroyed more than 175,000 acres of farmland in Somalia and Ethiopia by the end of December. They are eating 1.8m tonnes of vegetation a day across 350 sq km (135 sq miles), FAO says.

The organisation believes one swarm in Kenya covered an area 40km by 60km. The Desert Locust Information Service, run by the FAO, provides forecasts, early warning and alerts on the timing, scale and location of invasions and breeding.